On Wed, 13 Apr 2016, Dan van der Ster wrote: > Hi ceph-devel, > > Did anyone ever consider using madvise MADV_MERGEABLE to enable kernel > samepage merging for the ceph-osd? Typically this is used on kvm hosts > to dedupe the VM memories, but naively I was thinking that since our > osdmaps are duplicated (a few 100MB per daemon) we might profit as > well. Though, perhaps these maps are changing often enough that KSM > wouldn't help... no idea. > > Any thoughts here? My guess is not. Maybe if we only kept the encoded maps in memory there'd be a better chance of dedup (but we don't). And they do change reasonably quickly.. I've no idea what time interval KSM is expected to work over. The high-level plan here is to move toward supporting a single process with multiple OSD instances. That will allow for a shared OSDMap cache *and* let us consolidate/share TCP connections across hosts, which will have its own benefits. sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
